Public power is coming to Marin County, unless Pacific Gas and Electric Co. can block it in the courts or at the ballot box.

On Thursday night, Marin's fledgling public power agency, the Marin Energy Authority, set its rates and picked a company to buy electricity wholesale for many of the county's residents. Although some residents have worried about the program's possible costs, the authority could start selling power to its first customers by May.

If that happens, Marin County would become California's first to adopt a new form of public power called "community choice aggregation," using a law written in the wake of the state's energy crisis. Under community choice aggregation, cities and counties can buy electricity for their residents, while traditional utilities continue to own and operate the power grid.

San Francisco isn't far behind Marin, pushing forward on its own community choice plan. Other towns and counties are likely to follow, drawn by the promise of greater local control over electricity rates. In places such as San Francisco and Marin County, advocates also want to control - and increase - the amount of renewable power they use.

"We're stepping up and answering the call of, 'What are we going to do about climate change?' " said San Francisco SupervisorRoss Mirkarimi. "Everyone talks a good game, but we're right in there, working on the nuts and bolts to make this happen."

But PG&E won't make leaving easy.

The utility, California's largest, has a long, successful history of blocking efforts by cities to go into the public power business or join another utility. Although PG&E originally supported the law that created community choice aggregation, it is now backing an initiative for the June ballot that would make setting up such systems much harder.

Delivery lines

Marin Energy Authority officials say PG&E, based in San Francisco, has threatened not to deliver electricity to the authority over PG&E's power lines - an act the authority considers illegal. The utility also has threatened to sue the authority, demanding that it perform a full environmental impact report before starting operations, said Marin County Supervisor Charles McGlashan.

"That would be the rope they'd use to hogtie us until June, when they can kill us with the ballot measure," said McGlashan, who also serves as the energy authority's chairman. The measure would force local governments that want to compete with PG&E to win the approval of two-thirds of their voters first.

PG&E spokeswoman Katie Romans said that for now, the utility will concentrate on persuading its customers in Marin County to stick with the company.

The authority is a joint-powers agency formed by the county and all of its cities except Corte Madera, Larkspur, Novato and Ross. Starting next week, the energy authority will mail notices to residents, telling them that they can opt out of the new system if they would rather stay with PG&E. The company plans its own outreach campaign, urging its customers not to leave.

"We're just staying the course," Romans said. "We're going to continue to communicate with our customers about the risks of the plan."

PG&E's argument

PG&E maintains that power prices could rise under the new system, although the utility has already asked state regulators for permission to raise its own rates next year. Under the Marin Energy Authority's rates set on Thursday, most residents will pay the same amount for electricity, month by month, as they do with PG&E. Residents who want 100 percent of their electricity to come from renewable sources will pay an extra $3 to $6 per month.

Not all Marin County residents and officials have welcomed the public power plan. In December, the county's civil grand jury issued a report called "Marin Clean Energy: Pull the Plug," arguing that the effort's costs were too uncertain.

Some residents have complained that the local power effort isn't local enough: The authority has hired Shell Energy North America, a subsidiary of an international oil company, to do most of the actual work.